This invention relates to a device for shutting of the flow of fluid, such as gaseous fuel, in case of emergency such as an earthquake or accidental leakage of explosive gas.
In the case of an earthquake or accidental leakage of explosive gaseous fuel, it is required to shut off the flow of the gaseous fuel from a supply pipe or tank without fail to avoid secondary accidents caused by explosion of the gaseous fuel. It is desired that fluid shut-off device provided for such purpose not consume any electric power in the normal inoperative position and, once operated, maintain the operative shut-off position in spite of interruption of the electric current. A more important requirement is that such a fluid shut-off device have a very high reliability. To this end, it is desired that the device becomes operative by a very small amount of electric current and almost instantaneously after supply of the current. Also, the force for shutting off the flow of the fluid has to be sufficiently high.
The fluid shut-off devices hitherto provided could not satisfy the above requirements simultaneously. Also, the conventional devices of this kind have been relatively complex and expensive.
Accordingly, an object of the present invention is to provide a fluid shut-off device which is operable with high reliability by a small amount of electric current immediately after supply thereof.
Another object of the present invention is to provide a fluid shut-off device which can provide sufficient power to interrupt the flow of the fluid material when operated and which maintains the operated position until manually reset to an inoperative position.
A further object of the present invention is to provide a fluid shut-off device which is operated in connection with a detector of gas leakage or an earthquake.
Still another object of the present invention is to provide a fluid shut-off device which, once operated, holds the operated position without any supply of electric current.
Another object of the present invention is to provide a fluid shut-off device which is simple in structure and relatively inexpensive.